Reactive Hot Pressing and Properties of Nb ₂ AlC

Dense Nb 2 AlC ceramic was synthesized from NbC, Nb, and Al powder mixture at 1650°C and a pressure of 30 MPa for 90 min using an in situ reaction/hot‐pressing method. The reaction kinetics, microstructure, physical, and mechanical properties of the fabricated material were investigated. A thermal expansion coefficient of ∼8.1 × 10 −6 K −1 was measured in the temperature range of 30°–1050°C. At room temperature a thermal conductivity of ∼20 W·(m·K) −1 and a Vickers hardness of ∼4.5 GPa were determined. The material attained Young's modulus, four‐point bending strength and fracture toughness of ∼294 GPa, ∼443 MPa, and ∼5.9 MPa·m 1/2 , respectively. The nanolayered grains with a mean grain size of 17 μm contributed to the damage tolerance of this ceramic. Quenching from 600°, 800°, and 1000°C into water at room temperature resulted in decrease in bending strength from 443 MPa for the as‐synthesized Nb 2 AlC to 391, 156, and 149 MPa, respectively.

Ҳали таржима қилинмаган